The climate in the Volcanoes National Park is favorable for outdoor activities throughout the year. At times the area experiences extended rainfalls and heavy down pours, frequent mist, and cool temperatures.
The average day temperatures at the altitude of the national park’s Headquarters (about 2400 m) are around 11 to 19 degrees Celsius. The air becomes colder as one climbs higher on the slopes of the volcanoes. It is not exceptional to experience early morning temperatures around freezing point at around 3000m and the highest altitudes, it freezes every night once in a while , the summit of Mt. Karisimbi is completely covered with a cap of snow.
The area has 4 seasons in a year; The long dry season typically extends from mid-June till mid- September. It is followed by short rains from October to December and by a short dry season again in January and February. Then the long rains start will last until the end of May. This pattern is actually rather theoretical. It is often said that rain can fall at anytime some 300 days a year in the virunga . The volcanoes themselves are often shrouded in mist.
Rainfall is not evenly spread all across the virunga range. On the Rwandan side of the range, the western volcanoes (Mt. kasirimbi and Mt. Visoke) receive statistically more rain than the Eastern ones (Mt. Sabyinyo, Mt. M’Ghahinga and Mt. Muhabura.
The highest precipitations occur at elevations around 2500 to 2700 metres , which is about the current lower boundary of volcanoes national park. Higher up rainfall decreases significantly and the highest slopes of the highest volcanoes are actually much drier, even if they often disappear totally behind thick cloud formations . The average annual rainfall at the summit of Mt. Karisimbi is around 940 mm, about half the level of rainfall at 2500 m.
The virunga forest is a life giving water reservoir that acts as a sponge and also regulates the climate. Hundreds of thousands of people in Northwest Rwanda rely on the forest for their regular water supply.